Motor vehicles, such as automobiles, cars, trucks, motorcycles, boats, locomotives, airplanes, and the like, have emerged as the dominant form of human transportation in the modern world and are capable of transporting a human operator and passengers over great distances at great speeds relative to older forms of transportation. The speed at which a motor vehicle can travel can vary based on a number of factors, such as the type of motor vehicle being used, the material on which the motor vehicle is travelling, and the fluid through which the motor vehicle is travelling. In some cases, the speed at which a motor vehicle can travel can vary and range from between ten miles an hour up to above four hundred miles an hour. These speeds are enough to cause significant aerodynamic drag on the motor vehicle as it travels through a fluid. As a result, most motor vehicles are aerodynamically designed and use the concepts of fluid dynamics such that the fluid through which the car is travelling (e.g., air) can be directed over and around the body of the motor vehicle to achieve a reduction in drag relative to motor vehicles that are not aerodynamically designed. In addition, by aerodynamically designing the motor vehicle, the performance and gas mileage of the motor vehicle can be increased.
A significant portion of the drag forces applied to a motor vehicle during travel are a result of the external side view mirrors that generally protrude from the vehicle cabin. Each of FIGS. 1, 2, and 3, illustrate a common shape of a side view mirror. During travel, each of these mirrors is exposed to the oncoming flow of fluid, which increases the drag applied to the motor vehicle and reduces fuel efficiency. The drag percentage created by the external side view mirrors is greater for smaller and lighter vehicles (e.g., electric cars, Formula 1, Smart, Mini Cooper), which have an overall less capture area (e.g., the maximum cross-sectional area of the vehicle perpendicular to the vehicle moving direction) than larger motor vehicles traveling at the same speed. Therefore, drag forces can more readily decelerate smaller vehicles.
Apart from drag force, another product of a motor vehicle travelling through a fluid, such as air, is noise. Most noise created during travel and heard by an operator when operating the motor vehicle does not come from the engine. Instead, the noise is a product of the flow of fluid around the motor vehicle. In particular, the side view mirrors are one of the major sources of noise that the operator and any other occupants of the vehicle hear during travel.
Drag and noise are a direct result of the flow conditions created by the shape of the side view mirrors. For example, flow conditions such as high turbulent pressure fluctuations and vortex shedding create drag, noise, and a low base pressure behind the flat rear surface of the mirror as a motor vehicle travels through a fluid. In addition, these flow conditions create a condition referred to as base flow. An example of how vortex shedding is created by using a common side view mirror can be seen in FIG. 4, which illustrates the side view mirror travelling through air that is illustrated as streamlines travelling around the side view mirror. As illustrated, the flow conditions are a result of the side view mirror having a streamlined front surface and abruptly terminating in a flat back (e.g., the mirror).
The present disclosure provides a low noise low drag device that uses jet flow control to reduce the effects of base flow vortex shedding, and thereby reduce the noise and drag caused by the low drag low noise device during use. The present disclosure achieves this reduction in drag and noise by manipulating the flow of fluid (e.g., air) around the low drag low noise device to create directed jet(s) of air around the flat surface on the rear of the device (e.g., the mirror of a side view mirror) creating a virtual trailing edge, or boat-tail, that reduces or removes vortex shedding. Thus, the jet(s) produced by the low drag low noise devices described herein act to counter base flow and reduce drag and noise.